Sulfurized low polyunsaturated oils and lubricants containing them



United States Patent SULFURIZED LOW PQLYUNSATURATEDOILS AND LUBRICANTS CONTAINING THEM John E. Farhakand Paul Gibson, Chicago, 111., assignors No Drawing. Application July 19, 1950 Serial No. 174,782

6 Claims. (Cl. 25248.6)

This invention relates to the manufacture of sulfurized oils and has to do particularly with the manufacture of a sulfurized fatty oil base suitable for use in the preparation of cutting oils, motor oil additives, extreme pressure lubricants, and the like.

It has been customary heretofore to sulfurize certain fatty oils in the preparation of sulfurized'lubricants, such as blends of sulfurized fatty oils and mineral lubricating oils. The sulfurized fatty oil in such compositions serves as a means of providing sulfur in soluble form. The value of sulfur in certain lubricants is well known. The sulfur, for example, has the property of permitting rapid heat transfer and imparts high temperature and pressure resistance to the lubricant.

It is important in the manufacture of sulfurized lubricants that the sulfurized base be completely soluble in the mineral oil and that the color be as light as possible, because the color gives an indication of quality. The viscosity of sulfurized lubricants is also important, for example, the viscosity should be uniform and relatively low. Some sulfurized oils have a tendency to develop gummy materials on storage, and it is desirable to substantially retard this tendency. Furthermore, since sulfur is an important ingredient of sulfurized lubricants, it is advantageous that the oil have the property of maintaining in solution a high percentage of sulfur.

Sulfurized oils manufactured heretofore have been relatively dark in color, usually being over 8 N. P. A. (National Petroleum Association color standard). Also, the sulfurized base component of the sulfurized lubricants of the prior art has not been as soluble as desired in mineral lubricating oil. The latter is particularly true since the trend in the petroleum industry is to use .solvent refining, which has a tendency to decrease the solubility of common sulfur bases in the refined mineral oil.

Sulfurized bases which are commonly prepared from regular commercial fatty oils are often unstable, particu larly with respect to viscosity, color, and sludge formation, which is believed to be due to the polymerization of certain highly unsaturated constituents.

An object of the present invention is to provide a sulfurized base which has a light color, high solubility in mineral lubricating oils, good stability on storage and relatively high sulfur content.

Another object of the invention is to provide a sulfurized lubricant of low viscosity which remains stable on storage and exhibits improved operating properties.

A further object of the invention is to provide an improved method of manufacturing sulfurized oils.

An important feature of the present invention is the type of fatty oil which is used in the preparation of the sulfurizcd base. Instead of using an ordinary fatty oil, such as commercial animal or vegetable oils, we use an oil which has been specially treated prior to sulfurization. Ordinary fatty oils contain undesirable constituents which have an adverse effect on the properties of the sulfurized product.

We have discovered that a fatty oil intended for sule 2,824,067 lcfi Patented Feb. 18, 1958 furization may be significantly improved by partial hydrogenation. In the hydrogenation operation it is desirable to carry the hydrogenation to the extent necessary to eliminate substantially all polyunsaturated compounds. This extent may be determined by measuring the refrac tive index of the hydrogenated product. The degree of hydrogenation may be measured by predetermining the drop in the refractive index necessary to remove polyunsaturated groups. This predetermined drop in the refractive index value can then be used as a control in commercial operations. Usually, a drop in the refractive index of about 2 to 5 units is sufficient, although the exact figure will depend on the particular type ofoil used. The drop in iodine value is not so critical, but there is usually an appreciable drop depending on the type of oil and the nature of the subsequent treatments given the oil.

In accordance with the present invention, the hydro genated oil is next treated to remove the high melting point saturated constituents. This may be done either by seeding and pressing or by solvent crystallization, both of which operations are well known in the art. For example, the seeding and pressing is ordinarily done by gradually chilling the oil until the saturated constituents are crystallized, and then the product is pressed to separate the oil from the stearine. In solvent crystallization, a suitable solvent, such as propane, alcohol, acetone, methylethylketone, etc., is used to dissolve the product, and the solution is then chilled until the stearine crystallizes. The mixture is then filtered to remove the stearine. It is desirable to produce an oil having as low a pour point as possible. We have obtained satisfactory results with a pour point of around 30 to 35 F.

The base oil produced as outlined above may then be subjected to any Well known or preferred sulfurization. operation. The sulfurizing is customarily done by heating the oil to about 350 F. and adding thereto flowers of sulfur. The reaction is exothermic and usually no further heat is necessary after the reaction is started. In the event the temperature tends to rise above 400, it is desirable to provide cooling. Usually around 12 percent sulfur is used and any uncombined sulfur is filtered from the product. It may be desirable to blow a gas, such as air or nitrogen, through the resulting product to remove any hydrogen sulphide.

The sulfur base as prepared above may then be added to a suitable mineral lubricating oil. The type of oil will dep'edduponthe uses for which the oil is intended. For example, in the preparation of cutting oil, mineral lubricating oil of around viscosity at around 100 F. may be used. In the manufacture of motor oils containing sulfur base additives, a lubricating oil within the range of about 200 to 350 Say. sec. viscosity may be used. In preparing extreme pressure lubricants a much higher viscosity lubricating oil is necessary.

Example I Prime burning lard oil having an iodine value of about 72, pour point of 35, refractive index of about 42 units and polyunsaturate content ofabout ll percent was hydrogenated in the presence of a nickel catalyst at a temperature of about 350 to 400 F. with a pressure of about 30 pounds until the refractive index had dropped 2 points. The time consumed was about 30 minutes.

The hydrogenated product was chilled to about 40 F. over a period of five to seven days. The resulting product was cold-settled and the clear oil drawn off. The lower portion containing the stearine was filtered. The destearinized oil had a pour point of about 35 R, an iodine value of 72, and a polyunsaturate content of 4 percent. The destearinized oil was treated with about 12 percent sulfur at a temperature of about 350 F. for

approximately three hours. The resulting product had a viscosity of 400 Say. sec. at 100 F. and a color of 6+ N. P. A. The combined sulfur content was about 11% percent and the resulting oil was very soluble in solvent refined mineral oil.

EXAMPLE II The sulfurized base of Example I was dissolved in solvent refined mineral lubricating oil having a viscosity of 100 Say. sec. at 100 F. and a color of 2 N. P. A. at 100 F. A mixture of 80 percent mineral oil and percent of the sulfurized base produced a cutting oil of approximately 2 /2 percent sulfur content. The finished cutting oil had a color of approximately 4 N. P. A. with a viscosity of about 150 Say. sec. at 100 F. The product was stable in storage and showed improved cutting properties over similar oil made from ordinary commercial lard oil.

EXAMPLE III proximately to F. and the slurry was then filtered through a. rotary filter to remove the stearine. The filtered oil had an iodine number of 71.6, a pour point of F. and a polyunsaturate content of 5 percent.

The hydrogenated and destearinized oil was sulfurized as in Example I. The sulfurized base had a color of about 4 N. P. A. and approximately 400 Say. sec. viscosity and also was very soluble in solvent refined mineral oils. It had a pour point of about 35 F.

EXAMPLE IV In the preparation of an extreme pressure lubricant, the sulfurized base prepared as in Example II was dissolved in Mid-Continent pale (solvent refined) mineral oil having a viscosity of 200 Say. secs. at 100 F. A mixture of 5 percent of the sulfurized base oil, 5 percent of lead naphthenate, and 90 percent mineral oil produced a satisfactory gear lubricant for extreme pressure duty.

The sulfurized base prepared in accordance with the present invention usually has the following properties:

Pour point, F 30-40 Iodine value 71-76 Polyunsaturates, percent 1-5 Sulfur content, percent 10-18 Color, N. P. A 4-6 A sulfurized base made from lard oil according to the present invention usually tests as follows:

Pour point, F 30-35 Iodine value 71-73 Polyunsaturates, percent 1-5 Sulfur content, percent 11-14 Color, N. P. A 2-5 4 When the sulfurized base is made from horse oil in accordance with the present invention, the product will test about as follows:

Pour point, F 30-35 iodine value 72-75 Polyunsaturates, percent 2-5 Sulfur content, percent 12-15 Color, N. P. A 3-6 While we prefer to use animal oils, such as lard oil and horse oil as shown in the above examples, we may also use vegetable oils, such as soya bean oil, cottonseed oil, and corn oil.

The term polyunsaturates as used herein signifies compounds having two or more double bonds per acid radical.

Obviously, many modifications and variations of the invention as hereinbefore set forth may be made without departing from the spirit and scope thereof, and therefore only such limitations should be imposed as are indicated in the appended claims.

We claim:

1. A sulfurized fatty triglyceride oil comprising a partially hydrogenated unsaturated animal oil, having a polyunsaturate content of no more than about 5 percent, a pour point of about 30 to F., a color not in excess of about 6 N. P. A., and a sulfur content of about 10 to 18 percent.

2. A sulfurized lard oil having a pour point of about 30 to 35 F., polyunsaturate content of about 1 to 5 percent, sulfur content of about 11 to 14 percent, and a color of about 2 to 5 N. P. A., said sulfurized oil prepared by partially hydrogenating the lard oil, separating the stearine, and sulfurizing the hydrogenated and destearinated product.

3. A sulfurizecl horse oil having a pour point of about 30 to F., polyunsaturate content of 2 to 5 percent, sulfur content of about 12 to 15 percent, and a color of about 3 to 6 N. P. A., said sulfurized base prepared by partially hydrogenating horse oil, separating the stearine, and sulfurizing the hydrogenated and destearinized prodnot.

4. A lubricant comprising a mineral lubricating oil and about 5 to 20 percent of an unsaturated oil-soluble, sulfurized and destearinized fatty triglyceride oil which fatty triglyceride oil has a polyunsaturate content of no more than about 5 percent.

5. A lubricant as described in claim 4 wherein the fatty triglyceride oil is lard oil.

6. A lubricant as described in claim 4 wherein the fatty triglyceride oil is horse oil.

References Cited in the file of this patent UNITED STATES PATENTS 2,113,810 Lincoln et al Apr. 12, 1938 2,311,633 Blaso Feb. 23, 1943 2,403,234 Patterson July 2, 1946 

1. A SULFURIZED FATTY TRIGLYCERIDE OIL COMPRISING A PARTAILLY HYDROGENATED UNSATURATED ANIMAL OIL HAVING A POLYUNSATURATE CONTENT OF NO MORE THAN ABOUT 5 PERCENT, A POUR POINT OF ABOUT 30* TO 40*F., A COLOR NOT IN EXCESS OF ABOUT 6 N. P. A., AND A SULFUR CONTENT OF ABOUT 10 TO 18 PERCENT. 